1. Field of the Invention
The invention generally relates to a coordinate algorithm, in particular, to a coordinate algorithm of a touch panel.
2. Description of Related Art
As demands on multi-touch technology are increased, the projected capacitive touch technology has become one of mainstream touch panel technologies. As the human body is an excellent conductor, if the human body approaches a projected capacitive touch panel, the capacitance generated by combination of electrostatic charges between a transparent electrode (indium tin oxide, ITO) of the projected capacitive touch panel and the human body is increased. The position of a touched point may be known by detecting changes of electrostatic capacity of sensing lines on the projected capacitive touch panel.
However, for the projected capacitive touch panel, in order to sense a sufficient capacitance of the human body, the area of sensing pads needs to be considered, such that the sensing lines on the projected capacitive touch panel are limited, and the resolution of the projected capacitive touch panel is also limited. For example, in consideration of physical characteristics of the projected capacitive touch panel, the area of rhomboidal sensing pads on the sensing line is approximately 5 mm×5 mm, so as to maintain an appropriate sensing area.
Therefore, a common 3-inch projected capacitive touch panel approximately has 12x-direction sensing lines and 8 y-direction sensing lines. In this manner, when the 3-inch projected capacitive touch panel has the sensing lines of a 12×8 matrix, the projected capacitive touch panel can only have a coordinate resolution of 12×8. It is difficult to apply the projected capacitive touch panel with such a low resolution to current information products mostly requiring a high resolution.
Therefore, in order to increase the resolution of the projected capacitive touch panel, a coordinate algorithm of a touch panel is proposed in relevant technologies. However, when sensing a touch object at an edge thereof, the touch panel using the coordinate algorithm still has some defects, for example, a problem of linearity and accuracy offsets of a frame of the touch panel.